Drag your finger across the screen to move the dial. Lift your finger to enter a digit. Tap the big = button to calculate. Its an Apple Watch calculator that works like a combination lock.
Gently hold your finger on the screen to insert a decimal point.
The Watch app uses haptic feedback clicks to allow you to feel and hear the dial turning, but you can disable this in the settings screen. Firmly press the screen to access settings from the menu screen. The menu also allows you to undo your last entry, clear the calculator or review the on-device help.
Distinctive multi-tone complications allow quick access to the calculator from your watch face.
The included iPhone app displays a ticker tape history of the calculations performed on Apple Watch. The iPhone app itself is not a calculator.